1. Field
The present embodiments relate to a particle therapy device and method of designing a radiation path.
2. Related Art
A particle therapy device generally includes a particle acceleration unit, a particle beam delivery unit that is connected thereto, and a plurality of irradiation positions. The acceleration of the particles, for example, protons, pions, helium ions, carbon ions or oxygen ions, is done by a synchrotron or cyclotron. The accelerated high-energy particles are decoupled from the particle acceleration unit and directed into the particle beam delivery unit (also known as a high-energy beam transport system HEBT). For example, when using a synchrotron, a knock-out exciter decouples the high-energy particles from the particle acceleration unit. The HEBT delivers the high-energy particles to the irradiation position. The irradiation position is the location where the irradiation procedure is to take place.
For example, an irradiation position, which is also referred to as a treatment position below, is used to perform a tumor therapy of a patient. The patient is positioned in the particle beam path and exposed to the high-energy particles.
A distinction is made between a “fixed beam” treatment chamber and a “gantry-based” treatment chamber. A fixed beam treatment chamber has particles that impinge upon a treatment location from a fixed direction. In the gantry-based treatment chamber the particle beam is directed onto the treatment location of the gantry from different directions. The beam quality is monitored at an irradiation location referred to below as a checking location. Beam parameters such as particle energy, energy distribution, and beam intensity are monitored at the checking location by means of quality measurements.
Demanding requirements are placed on the safety of a particle therapy facility. For example, the particle beam must only be delivered to an irradiation position that is prepared for an irradiation procedure and has requested the particle beam. The particle beam must also have the correct requested parameters. Rapid interruption of the particle delivery is necessary in the event of an emergency. The HEBT, for example, features a baffle. The baffle allows the particle beam to be quickly cut off. A control and safety system of the particle therapy device is generally used to check and direct a particle beam having the required parameters into the relevant treatment chamber.
The required parameters are defined in the treatment plan (therapy plan). The treatment plan specifies how many particles should hit the patient, from what direction and with what energy. The energy of the particles determines the penetration depth of the particles into the patient. The location where the maximum interaction occurs with the tissue during the particle therapy is the location where the maximum dose of particles is deposited. The parameters required by the treatment plan are usually converted by an accelerator control unit into configuration parameters, for example, in the form of machine parameters, for the accelerator and particle beam delivery unit. The information describing the irradiation position to which the particle beam must be guided is converted into configuration parameters for the particle beam delivery unit. A control unit of the irradiation position controls a positioning device. The positioning device is dependent on the position of a patient who must be irradiated or phantom material which must be irradiated in relation to the particle beam.
A particle therapy facility including a plurality of fixed-beam treatment positions and a gantry is disclosed in EP 0 986 070. Various irradiation facilities and techniques are described by H. Blattmann in “Beam delivery systems for charged particles”, Radiat. Environ. Biophys. (1992) 31:219-231. A method for selecting a treatment room is disclosed in U.S. Pat. No. 5,260,581 and a control and safety system for an irradiation therapy facility is disclosed in U.S. Pat. No. 5,895,926.